It is known to provide nozzles with different diameters for petrol fuel on the one hand and diesel fuel on the other hand. These measures were introduced following the need to differentiate unleaded petrol fuel from leaded fuel. The nozzles for unleaded petrol fuel have a smaller external diameter than the nozzles for leaded fuel and for diesel fuel. Misfueling a diesel vehicle with petrol fuel is however not ruled out if special precautions are not made for this. It is known from DE 101 26 207 to lock a flap which can be pivoted about a transverse axis in the insertion path of the nozzle in the closed state. The locking is formed by a plurality of radially arranged, circumferentially spaced segments which form a conical entrance portion. If a petrol nozzle is inserted the segments remain in their resting position and the nozzle strikes against the locked flap. The diesel nozzle, however, radially displaces the locking segments and thereby unlocks the flap so that the nozzle can open the flap. Misfuelling by handling the petrol nozzle to remove the locking is not ruled out.
In DE 101 39 665 and DE 101 26 209 filler necks for diesel fuel are known which are designed such that when inserting a diesel nozzle a filling valve opens. When inserting an petrol nozzle, however, the valve is either not actuated so that the petrol fuel remains in the front region of the filler neck or the flow is throttled to such an extent that the nozzle automatically cuts out. The nozzles are known to contain a mechanism which closes the valve in the nozzle as soon as a certain back pressure is generated. As a result, the priority is to avoid overfilling the tank.
The known filler necks require a relatively large amount of space to be constructed and are relatively expensive. Furthermore they cannot be used for so-called capless filling systems. By this is understood filling systems which allow the tank to be automatically refuelled. The filler neck is no longer sealed by a specific cap but the nozzle can be directly inserted. In this connection it is known from FR 2761934 to provide a closure cap on the end of a filler neck. It opens inwardly and is provided with a seal which cooperates with a sealing edge in the interior of the pipe. When refueling the flap is pivoted open by the nozzle against the force of a spring. The object of the flap is to prevent contaminants from entering the tank. Opening the flap requires a relatively large amount of force as the spring has to prevent pressurised spray water, for example, from inadvertently opening the flap.
The object of the invention is to produce a filler neck for filling fuel into a vehicle tank which requires very little space for its construction and few components to prevent misfueling and which is also suitable for use in connection with capless filling systems and offers protection against the penetration of undesirable media into the tank.